c
c
c
c     =====================================================
       subroutine qinit(maxmx,maxmy,meqn,mbc,mx,my,xlower,ylower,
     &                   dx,dy,q,maux,aux)
c     =====================================================
c
c     # Set initial conditions for q.
c
       implicit double precision (a-h,o-z)
       dimension q(1-mbc:maxmx+mbc, 1-mbc:maxmy+mbc, meqn)
c
       pi = 4.d0*datan(1.d0)
       width = 0.2d0

       do 20 i=1,mx
          xc = xlower + (i-0.5d0)*dx
          do 20 j=1,my
             yc = ylower + (j-0.5d0)*dy

c            # map the center of this computational cell to physical
c            # coordinates before evaluating the initial value funcion:
             call mapc2p(xc,yc,xp,yp)
             r = dsqrt(xp**2 + yp**2)

             if (dabs(r-0.5d0) .le. width) then
                 pressure = 1.d0 + dcos(pi*(r - 0.5d0)/width)
               else
                 pressure = 0.d0
               endif
             q(i,j,1) = pressure
             q(i,j,2) = 0.d0
             q(i,j,3) = 0.d0

  20         continue
       return
       end